The present invention relates to an inductively coupled plasma mass spectrometric and spectrochemical analyzer, and more particularly to an organic solvent sample introducing apparatus.
A conventional inductively coupled plasma mass spectrometric analyzer is structured, as shown in FIG. 2, by a plasma-generating torch 4 and a chamber 9 connected to the torch 4 for serving as a sample introducing section. The chamber 9 is provided with a support member 12 at one end through an O-ring 11. The support member 12 is fitted with a nebulizer 13 to atomize a sample 18. The sample 18 contained in a sample vessel 17 is supplied through a sample supply tube 16 to the nebulizer 13. Here, a nebulizer gas reserved in a nebulizer gas supply section 15 is supplied to the nebulizer 13 through a nebulizer gas supply tube 14. The sample 18 is atomized by this nebulizer 13 and then introduced to the torch 4 by way of the chamber 9. The chamber 9 has a drain port 10 at its lowermost portion to discharge a waste solution.
The torch 4 is structured by coaxial triple pipes so that the sample 18 introduced from the chamber 9 passes through an innermost pipe 5 of the three pipes into a plasma 2. The sample 18 is ionized in the plasma 2 and analyzed by a mass spectrometer (not shown) after passing through an aperture formed in a sampling cone 1 composing an analyzing section of the inducively coupled plasma analyzer. The innermost pipe 5 of the torch 4 has thereover an intermediate pipe 8a through which an auxiliary gas is passed from an auxiliary gas supply port 8. The intermediate pipe 8a has thereover an outermost pipe 24 through which a plasma gas (a gas that itself is later turned into a plasma by an application of an radio-frequency electric power) is supplied to a tip of the torch 4.
The chamber 9 has an exit pipe 23 to introduce the finely atomized sample into the innermost pipe 5. The innermost pipe 5 and the exit pipe 23 are connected at their ends in a fluid connection by means of a clamp 6.
Where the sample 18 to be introduced is an organic solvent, the carbon C contained in the introduced sample tends to adhere to the tip of the torch 4 or the aperture of the sampling cone 1, causing plugging or decrease in analytical sensitivity. To avoid this, a gas introducing port 21 is provided in the support member 12 to supply therethrough an oxygen gas into the chamber 9 where the oxygen gas is mixed with the sample 18 and introduced into the plasma 2, thereby solving the problem. That is, the carbon C contained in the sample 18 mixed with the oxygen gas is burnt in the plasma 2 and turned into carbon dioxide CO.sub.2 or carbon monoxide CO. Since such carbon dioxide CO.sub.2 or carbon monoxide CO passes through the aperture of the sampling cone 1 or dissipated to the atmosphere, there is no carbon adhesion to the tip of the torch 4 or the aperture of the sampling cone 1.
In the above-stated prior art, however, the oxygen gas introduced through the gas introducing port 21 in the support member 12 and the organic solvent atomized through the nebulizer 13 fixed on the support member 12 are mixed within the chamber 9. At this time, if static electricity, back fire, radio frequency wave or the like causes the organic solvent mixed with the oxygen gas present within the chamber 9 to be ignited, there is a fear of burst of the chamber 9. To avoid this, the introducing amount of the oxygen gas must be kept low. However, where the amount of the introduced oxygen gas is reduced lower than the amount required to sufficiently burn the carbon C of the sample, the carbon C is not sufficiently turned into carbon dioxide CO.sub.2 or carbon monoxide CO, thus resulting in plugging at the tip of the torch 4 or the aperture of the sampling cone 1 and hence decrease in analytical sensitivity.
It is an object of the present invention to provide an inductively coupled plasma mass spectrometric analyzer which is capable of solving the above-stated problem, preventing plugging and enabling high sensitivity measurement without a fear of bursting the chamber 9 even if the oxygen gas flows in a sufficient amount for suppressing the plugging at the tip of the torch 4 or the sampling cone 1 as well as the decrease in sensitivity due to the carbon C contained in a sample.